Noise reduction in a wide variety of environments such as buildings, vehicles, i.e., equipment, etc., is generally considered as desirable. For example, in vehicles such as automobiles it is highly desirable to reduce the external noises, namely road noise, wind noise, engine noise, vibrations as well as internal noises through the use of various acoustic materials.
Often, acoustic engineers attempt to achieve sound attenuation by the use of various acoustic materials. For example, so-called scrim layers are often used over thick low density spacer materials and voids located in floor panels, headliners and door panels of a vehicle. One example is the use of perforated films as described in U.S. Pat. No. 4,097,633. It is believed, however, that various production and quality issues are problematic in this approach. Microfiber scrims have also been proposed and used in a multilayer acoustically tuned sound absorbing composite such as described in U.S. Pat. No. 6,631,785. Other examples of various scrim layers include U.S. Pat. Nos. 5,186,996; 5,298,694; 5,886,306; 6,145,617; 7,310,739; and U.S. Patent Application Publication No. 2007/051800.
However, there continues to be a need for acoustic materials having improved sound absorbing properties, wherein such materials are low in thickness, low in weight, low in cost, and provide the necessary safety and sound absorption properties.